1. The Field of the Invention
The present invention relates to stone etching. In more particular, the present invention relates to methods and apparatus for etching designs into the surface of stone or other solid surface materials using a combination of a laser and a corrosive agent application.
2. Background and Relevant Art
For centuries people have utilized stone as a medium of expression. Stone is particularly desirable due to the ability of stone to withstand the effects of time and the elements to memorialize words and depictions engraved in the stone. Anciently, skilled artisans used tools such as chisels and scribes to etch or otherwise engrave words and such depictions and designs into the surface of the stone. The greater the depth of such etchings and engravings the longer amount of time such engravings can be maintained on the surface of the stone. While etching and engraving stone has provided an effective mechanism for memorializing such renditions, such etchings and engravings requires an extensive amount of time and effort, making stone engraving quite expensive. As a result, stone engraving has been reserved for very specific applications where the desire to memorialize such engravings justifies the cost associated with creating such engravings. For example, stone engravings are most frequently utilized in graveyard headstones, public memorials, and the like.
In addition to conventional mechanical engraving of stone, chemical applications have also been developed to allow for less time consuming and more cost effective engraving in stone. One traditional mechanism involves the application of a mask material to the surface of the stone. The mask material can be applied in a sheet such as latex which is adhered to the surface of the stone or as a removable layer, such as a wax or rubber layer. Once the mask is applied to the surface of the stone, portions of the mask are removed to form letters, depictions, or other designs. The removal of selective portions of the mask exposes the corresponding portions of the surface of the stone. The portions of the stone which correspond to the unremoved portions of the mask are protected by contact with the mask.
Once the design has been created in the mask, a corrosive agent is then applied to the mask and stone slab. The corrosive agent cuts into those portions of the stone that have been exposed by removal of the mask. The portions of the stone which remain in contact with the mask are protected from exposure to the corrosive agent by the mask itself. Once the corrosive agent has achieved the desired depth in the exposed portions of the stone, the corrosive agent is removed or neutralized and the mask is removed. Once the mask is removed, the exposed engravings and depictions that were originally inscribed in the mask layer have been memorialized in the stone. While the use of a corrosive agent in combination with a mask is less time consuming than traditional mechanical engraving, a fair amount of time and energy must be utilized to remove the mask portions required to form the design. Again, this can substantially limit the type and number of applications in which stone engraving can be utilized. Additionally, the amount of detail and intricacy of such engravings are limited due to time and technical constraints involved in using the mask and corrosive agent combination.
Laser etching or laser engraving into stone and other hard surface materials has allowed for both less labor intensive engraving processes while also allowing a greater degree of detail and intricacy than can be utilized in other stone engraving processes. Laser etching typically involves exposing the material to the focal point of a laser beam causing the energy from the beam to remove or otherwise affect the material exposed. Modern laser systems allow images to be electronically stored and then automatically engraved through automated processes. While laser etching allows for the use of such automated processes and designs having a greater degree of detail, the depth of laser engravings are typically limited to a vary slight etch in the surface of the material. Typically, the depth of such etching is barely detectable to tactile perception.
As a result, while images and other engravings can quickly be formed into stone and other hard surface materials, exposure to outdoor elements quickly deteriorates the quality of such images, minimizing their potential applicability in traditional stone engraving applications. Applying higher amounts of energy during laser etching can result in deeper etching. However, higher amounts of energy typically cause the particles of the material to pop or burst resulting in an uneven and unpredictable appearance. As a result, laser etching is typically utilized where only slight surface etching is required.
Because of the very slight depth provided by laser etching, such laser etchings are only clearly perceptible in dark colored materials having fairly uniform color and surface texture. In an attempt to expand the number and types of materials for which laser etching can be utilized, special coatings have been developed which change color when applied to the laser energy. These coatings have had limited success in providing greater clarity to images in some solid surface materials, but can often produce undesirable and unnatural effects when used with stone, tile, or other hard surface materials. Additionally, the limitations with regard to the depth of such etching are still readily apparent.